Electronic device comprising electrical contact pads

ABSTRACT

An electronic device and a method of fabricating the same are provided. The electronic device includes: a photodiode layer; a wiring layer formed on the first surface of the photodiode layer; a plurality of electrical contact pads formed on the wiring layer; a passivation layer formed on the wiring layer and the electrical contact pads; an antireflective layer formed on the second surface of the photodiode layer; a color filter layer formed on the antireflective layer; a dielectric layer formed on the antireflective layer and the color filter layer; and a microlens layer formed on the dielectric layer, allowing the color filter layer, the dielectric layer and the microlens layer to define an active region within which the electrical contact pads are positioned. As the electrical contact pads are positioned within the active region, an area of the substrate used for an inactive region can be eliminated.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims under 35 U.S.C. §119(a) the benefit of TaiwaneseApplication No. 099123521, filed Jul. 16, 2010, the entire contents ofwhich is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to electronic devices and methods offabricating the same, and, more particularly, to an electronic devicehaving conductive contact pads and a method of fabricating the same.

2. Description of Related Art

A general electronic component or semiconductor chip is an integratedcircuit (IC) capable of processing electronic signals fabricated byforming multiple dielectric layers and metal layers on a siliconsubstrate. In recent years, a flourished complementary metal oxidesemiconductor (CMOS) image sensor is an electronic device constructed onthe basis of a standard semiconductor process, which is generally usedin the photography module of a digital camera or a mobile phone.

Referring to FIG. 1, a cross-sectional view of an electronic device suchas a CMOS image sensor in accordance with the prior art is shown. Theelectronic device has: a carrier board 10 having a first surface 10 aand a corresponding second surface 10 b; a first electrical contact pad11 formed on the first surface 10 a; a wiring layer 12 formed on thefirst surface 10 a and the first electrical contact pad 11, the wiringlayer 12 being electrically connected to the first electrical contactpad 11; a silicon layer 13 formed on the wiring layer 12; a color filterlayer 14 formed on the silicon layer 13; a microlens layer 15 formed onthe color filter layer 26, allowing the color filter layer 14 and themicrolens layer 15 to define an active region A, wherein a regionoutside the active region A is an inactive region B, and the firstelectrical contact pad 11 is positioned outside the active region A; asecond electrical contact pad 16 formed on the second surface 10 b; aglass layer 17, formed on the second surface 10 b and having a opening170 for exposing the second electrical contact pad 16; and a conductiveaperture 18 penetrating through the carrier board 10 and electricallyconnected to the first electrical contact pad 11 and the secondelectrical contact pad 16.

However, since the first electrical contact pad 11 of the electronicdevice is disposed outside the active region of the electronic device,the whole electronic device occupies a larger area of the substrate(including the carrier, the wire-disposing layer, the silicon layer andthe like) and is thus larger in size. That is, the disposition of thefirst electrical contact pad 11 of the prior art electronic devicerequires a larger size of the substrate, thereby making the electronicdevice higher in cost to manufacturer and larger in size. Accordingly,such an electronic device fails to meet the miniaturization requirementfor electronic products.

Therefore, it has become a critical issue to be solved as to how toeffectively reduce the required size of the substrate.

SUMMARY OF THE INVENTION

In view of the above-mentioned problems of the prior art, the primaryobject of the present invention is to provide an electronic devicehaving a smaller substrate area and a method of fabricating the same.

In order to achieve the above-mentioned and other objects, the presentinvention provides an electronic device, comprising: a photodiode layerhaving corresponding first and second surfaces; a wiring layer formed onthe first surface of the photodiode layer, the wiring layer comprising aplurality of wires spaced apart from each other and disposed in aspecial arrangement and a plurality of transfer gates disposed atpositions proximate to the photodiode layer; a plurality of electricalcontact pads formed on the wiring layer and electrically connected tothe wiring layer; a passivation layer formed on the wiring layer and theelectrical contact pads; an antireflective layer formed on the secondsurface of the photodiode layer; a color filter layer formed on theantireflective layer; a dielectric layer formed on the antireflectivelayer and the color filter layer; and a microlens layer formed on thedielectric layer, allowing the color filter layer, the dielectric layerand the microlens layer to define an active region within whichelectrical contact pads are positioned.

In the above-mentioned electronic device, the electrical contact padscan be embedded in the wiring layer and exposed from a surface of thewiring layer. Alternatively, the electrical contact pads are in theshape of a pillar and penetrate the passivation layer.

In the aforementioned electronic device, the photodiode layer can bemade of amorphous silicon, and the passivation layer can be made of amaterial selected from the group consisting of silicon oxide, epitaxialsilicon, and polyimide.

In the aforementioned electronic device, a carrier board can be furtherdisposed on the passivation layer.

The present invention further provides a method of fabricating anelectronic device, comprising: forming a photodiode layer on a siliconsubstrate; forming a wiring layer on the photodiode layer, the wiringlayer comprising a plurality of wires spaced apart from each other anddisposed in a special arrangement and a plurality of transfer gatesdisposed at positions proximate to the photodiode layer; forming aplurality of electrical contact pads on the wiring layer andelectrically connecting the electrical contact pads to the wiring layer;forming a passivation layer on the wiring layer and the electricalcontact pads; attaching a carrier board on the passivation layer;removing the silicon substrate; forming an antireflective layer on thephotodiode layer; forming a color filter layer on the antireflectivelayer; forming a dielectric layer on the antireflective layer and thecolor filter layer; and forming a microlens layer on the dielectriclayer, allowing the color filter layer, the dielectric layer and themicrolens layer to define an active region within which the electricalcontact pads are positioned.

According to the above-mentioned method of fabricating the electronicdevice, the electrical contact pads can be embedded in the wiring layerand exposed from a surface of the wiring layer. Alternatively, theelectrical contact pads can be in the shape of a pillar and penetratethrough the passivation layer.

In the above-mentioned method of fabricating the electronic device, thephotodiode layer can be made of amorphous silicon, and the passivationlayer can be made of a material selected from the group consisting ofsilicon oxide, epitaxial silicon, and polyimide.

In the method of fabricating the electronic device, a planarizationprocess is further performed to the passivation layer after forming thepassivation layer.

In conclusion, the electronic device of the present invention providesthe electrical contact pads within the active region. Therefore, as anarea of the substrate used for an inactive region can be eliminated, andthe electronic device can be reduced in size such that miniaturizationrequirement for electronic products can be met. In addition, theelectrical contact pad of the present invention can be a conductivepillar. Whereby the electronic device of the present invention is ofimproved flexibility in structural design.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view of an electronic device such as a CMOSimage sensor in accordance with the prior art;

FIGS. 2A-2G are cross-sectional views of an electronic device and amethod of fabricating the same in accordance with the present invention,where FIG. 2D′ is another implementation aspect of FIG. 2D, FIG. 2E′ isanother implementation aspect of FIG. 2E, and FIGS. 2G′ and 2G″ areother implementation aspects of FIG. 2G; and

FIGS. 3A-3C are schematic comparison diagrams of substrates of theelectronic devices in accordance with the prior art and the presentinvention, wherein FIG. 3A is a plan view of the substrate of theelectronic device in accordance with the prior art, FIG. 3B is a planview of the substrate of the electronic device in accordance with thepresent invention, and FIG. 3C is a schematic view showing a differencein size between the substrate of the present invention and that of theprior art in light of FIGS. 3A and 3B.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The following specific embodiments are disposed to illustrate thedisclosure of the present invention, these and other advantages andeffects can be apparently understood by those in the art after readingthe disclosure of this specification.

Referring to FIGS. 2A-2G, cross-sectional views of an electronic deviceand a method of fabricating the same in accordance with the presentinvention are shown, wherein FIGS. 2G′ and 2G″ are other implementationaspects of FIG. 2G.

As illustrated in FIG. 2A, a silicon substrate 20 is provided.

As illustrated in FIG. 2B, a photodiode layer 21 is formed on thesilicon substrate 20. The photodiode layer 21 can be made of amorphoussilicon.

As illustrated in FIG. 2C, a wiring layer 22 is formed on the photodiodelayer 21. The wiring layer 22 comprises a dielectric body 220 formed onthe photodiode layer 21, a plurality of wires 221 spaced apart from eachother in the dielectric body 220 and disposed in a special arrangement,and a plurality of transfer gates 222 disposed in the dielectric body220 at positions proximate to the photodiode layer 21. A plurality ofelectrical contact pads 23 are formed on the wiring layer 22 andelectrically connected to the wires 221.

As illustrated in FIG. 2D, a passivation layer 24 is formed on in thedielectric body 220 of the wiring layer 22 and the electrical contactpads 23. The passivation layer 24 can be made of silicon oxide,epitaxial silicon, or polyimide. A planarization process can be furtherperformed to the passivation layer 24 after the passivation layer 24 isformed.

As illustrated in FIG. 2E, a carrier board 30 is attached to thepassivation layer 24. In FIGS. 2D′ and 2E′, electrical contact pads 23′(see also FIG. 2G″) are formed on the dielectric body 220 of the wiringlayer 22, and are in the shape of a pillar.

As illustrated in FIG. 2F, the silicon substrate 20 is removed; and anantireflective layer 25 is formed on the photodiode layer 21.

As illustrated in FIG. 2G, a color filter layer 26 is formed on theantireflective layer 25; a dielectric layer 27 is formed on theantireflective layer 25 and the color filter layer 26; and a microlenslayer 28 is formed on the dielectric layer 27. The region formed withthe color filter layer 26, the dielectric layer 27, and the microlenslayer 28 is defined as an active region A. The electrical contact pads23 are positioned within the active region A.

As illustrated in FIG. 2G′ which is another implementation aspect ofFIG. 2G, the electrical contact pads 23 are embedded in the wiring layer22 and exposed from a surface of the wiring layer 22.

As illustrated in FIG. 2G″ which shows a continuous fabrication of FIG.2E′ and is a further implementation aspect of FIG. 2G, the electricalcontact pads 23′ are in the shape of a pillar and penetrate through thepassivation layer 24 without penetrating into the dielectric body 220 ofthe wiring layer 22.

In light of the above, the electronic device provided by the presentinvention has: a photodiode layer 21 having corresponding first andsecond surface 21 a, 21 b; a wiring layer 22 formed on the first surface21 a of the photodiode layer 21, the wiring layer 22 comprising aplurality of wires 221 spaced apart from each other and disposed in aspecial arrangement and a plurality of transfer gates 222 disposed atpositions proximate to the photodiode layer 21; a plurality ofelectrical contact pads 23 formed on the wiring layer 22 andelectrically connected to the wires 221; a passivation layer 24 formedon the wiring layer 22 and the electrical contact pads 23; a carrierboard 30 disposed on the passivation layer 24; an antireflective layer25 formed on the second surface 21 b of the photodiode layer 21; a colorfilter layer 26 formed on the antireflective layer 25; a dielectriclayer 27 formed on the antireflective layer 25 and the color filterlayer 26; and a microlens layer 28 formed on the dielectric layer 27,allowinga region formed with the color filter layer 26, the dielectriclayer 27, and the microlens layer 28 to be defined as an active regionA. The electrical contact pads 23 are positioned within the activeregion A.

In the above-mentioned electronic device, the electrical contact pads 23can be embedded in the wiring layer 22 and exposed from a surface of thewiring layer 22. Alternatively, the electrical contact pads 23′ are inthe shape of a pillar and penetrate through the passivation layer 24.

In this embodiment, the photodiode layer 21 can be made of amorphoussilicon, and the passivation layer 24 can be made of a material selectedfrom the group consisting of silicon oxide, epitaxial silicon, andpolyimide.

Referring to FIGS. 3A-3C, schematic diagrams of a difference in size orarea between the substrate for the electronic device in accordance withthe present invention and that in accordance with the prior art areshown. FIG. 3A is a plan view of the substrate of the electronic devicein accordance with the prior art, FIG. 3B is a plan view of thesubstrate of the electronic device in accordance with the presentinvention, and FIG. 3C is a schematic view of the difference in size orarea between FIG. 3A and FIG. 3B.

As illustrated in FIG. 3A, a plurality of first electrical contact pads11 are formed in an inactive region B outside the active region A inaccordance with the electronic device of the prior art. Therefore, theoverall substrate area is the summation of the active region A andinactive region B.

As illustrated in FIG. 3B, the first electrical contact pads 23(equivalent to the first electrical contact pads 11) are formed withinthe active region A in accordance with the electronic device of thepresent invention. Therefore, the overall area of the substrate(including the photodiode layer 21, the wire-disposing layer 22, thecarrier board 30 and the like) equals to the area of the active region Aand is thus smaller than that of the prior art substrate as illustratedin FIG. 3A.

As illustrated in FIG. 3C, an area difference 5 is equal the substratearea illustrated in FIG. 3A subtracted by the substrate area illustratedin FIG. 3B. As shown, the electronic device of the present invention isallowed to employ a substrate with a smaller size than the prior art andthus the cost for fabricating the same is reduced.

In conclusion, compared with the prior art, the electrical contact padsof the electronic device of the present invention are positioned withinthe active region, such that the area of the substrate for the inactiveregion becomes unnecessary and can thus be eliminated. Further, the sizeof the electronic device can be reduced due to the reduced size of thesubstrate, and thus can meet the miniaturization requirement forelectronic products. In addition, the electrical contact pads of thepresent invention can be conductive pillars, whereby the electronicdevice of the present invention is flexible in structural design.

The above-mentioned embodiments are used to exemplarily illustrate theprinciples and effects of the present invention and are not restrictiveof the scope of the present invention. One skilled in the art couldmodify the above-mentioned embodiments without violating the spirit andscope of the present invention. Hence, the protected scope of thepresent invention should fall within the following appended claims.

What is claimed is:
 1. An electronic device, comprising: a photodiodelayer having corresponding first and second surfaces; a wiring layerformed on the first surface of the photodiode layer and comprising adielectric body formed on the photodiode layer, a plurality of wiresspaced apart from each other in the dielectric body and disposed in aspecial arrangement, and a plurality of transfer gates disposed in thedielectric body at positions proximate to the photodiode layer; aplurality of electrical contact pads formed on the wiring layer andelectrically connected to the wiring layer; a passivation layer formedon the wiring layer and the electrical contact pads, wherein theelectrical contact pads penetrate through the passivation layer withoutpenetrating into the dielectric body of the wiring layer; anantireflective layer formed on the second surface of the photodiodelayer; a color filter layer formed on the antireflective layer; adielectric layer formed on the antireflective layer and the color filterlayer; and a microlens layer formed on the dielectric layer, allowingthe color filter layer, the dielectric layer and the microlens layer todefine an active region within which the electrical contact pads arepositioned.
 2. The electronic device of claim 1, wherein the electricalcontact pads are embedded in the wiring layer and exposed from a surfaceof the wiring layer.
 3. The electronic device of claim 1, wherein thephotodiode layer is made of amorphous silicon.
 4. The electronic deviceof claim 1, wherein the electrical contact pads are in the shape of apillar.
 5. The electronic device of claim 1, wherein the passivationlayer is made of a material selected from the group consisting ofsilicon oxide, epitaxial silicon, and polyimide.
 6. The electronicdevice of claim 1, further comprising a carrier board disposed on thepassivation layer.